Engineers from The Chinese University of Hong Kong have developed miniature, shape-shifting robots that can rapidly alternate between liquid and solid states.

Inspired by the shape-shifting sea cucumber, the engineers developed the phase-shifting material called "magnetoactive solid-liquid phase transitional machine.” To develop this new material, magnetic particles were embedded in gallium, which is a metal featuring an extremely low melting point — 29.8° C.

Source: Wang and Pan et al.

"The magnetic particles here have two roles," explained the researchers. "One is that they make the material responsive to an alternating magnetic field, so you can, through induction, heat up the material and cause the phase change. But the magnetic particles also give the robots mobility and the ability to move in response to the magnetic field."

According to the researchers, this is in contrast to current phase-shifting materials that rely on external heat sources to encourage solid-to-liquid transformation.

During tests in the lab, the team demonstrated that, using a magnetic field, the robots could jump over moats, climb walls and split in half to jointly move objects before re-joining.

In one test, the researchers demonstrated that a person-shaped robot composed of the material could escape a cage-like structure, by first liquifying and then remolding back into its original shape.

Further, the team demonstrated that the robots could be used to remove a foreign object from a model stomach as well as deliver drugs on-demand into that model stomach.

In addition to such biomedical applications, the material could be used to create smart soldering robots for wireless circuit assembly and repair or to create a universal mechanical screw that can be used to assemble parts in hard-to-reach spaces.

An article detailing the shape-shifting robots, Magnetoactive Liquid-Solid Phase Transitional Matter, appears in the journal Matter.

For more information on the shape-shifting material, watch the accompanying video that appears courtesy of Wang and Pan et al.